Heat storage materials are made of materials containing large heat capacity substances. Heat stored in such a substance in a heat storage material can be removed from the heat storage material, as needed. Conventionally, water is commonly used as a heat storage material. In most cases, however, the form of heat storage using water as a heat storage material depends on the use of sensible heat resulting from a change in the temperature of water. Therefore, in order to further increase the amount of stored heat, the use of a heat storage material that can store latent heat associated with its phase change has attracted attention as another form of heat storage.
Known heat storage materials that can store latent heat include hydrate, water (ice), and paraffin. These heat storage materials are fluidized as their phase changes. Therefore, in order to prevent the fluidized heat storage materials from drifting with heat media and leaking, they are usually placed in containers when they are used.
As shown in FIG. 11, Patent Literature 1 discloses a heat storage device 100 in which a hydrate is used as a heat storage material. The heat storage device 100 includes heat storage means 104, heat transfer walls 105, and fluid passages 106. The heat storage means 104 each have a latent heat storage agent 103 formed in a flat plate shape and an aluminum-laminated film bag 102 in which the latent heat storage agent 103 is vacuum-sealed. The heat transfer walls 105 hold the heat storage means 104 therebetween. Each of the heat transfer walls 105 is formed of two regularly corrugated copper plates that are joined together. The fluid passages 106 are formed between the two copper plates. The heat storage means 104 is heated or cooled by a heat medium (for example, water) flowing in the fluid passages 106. As the latent heat storage agent 103, sodium acetate trihydrate is used.
Patent Literature 2 discloses a heat storage material containing a paraffin compound. This heat storage material contains the paraffin compound and a hydrogenated diene copolymer having a function of fixing the paraffin compound. Thereby, this heat storage material has properties such that it is free from phase separation or liquid phase bleeding even at or above the maximum crystal transition temperature Tmax of the paraffin compound as a component of the material and that it has excellent shape stability and excellent fluidity during forming.